1. Field of the Invention
The present invention relates generally to a local Ni plating method for aluminum alloy radiators, which is suited for Ni plating terminals of an aluminum alloy radiator structure, i.e., the connecting ends of the aluminum alloy radiator to connect a copper base. According to the claimed invention, the new Ni plating method improves the uniformity of nickel-plating layer plated on the terminals of the radiator. The appearance of the radiator is meliorated and the heat-dissipating performance of the aluminum alloy radiator is significantly enhanced. Further, excess zinc residuals left on the aluminum alloy radiator can be recovered from the Ni plating process.
2. Description of the Prior Art
A prior art aluminum-copper combined radiator typically consisting of a copper base and an aluminum alloy fin structure mounted on the copper base is known in the art. To tightly joint the aluminum alloy fin structure and the copper base together, a lay of nickel is plated onto the connecting ends of the aluminum alloy fin structure, a solder paste is then coated on the nickel layer. FIG. 1 illustrates a process flow of a prior art method of locally nickel-plating an aluminum alloy radiator 1a. FIG. 2 and FIG. 3 are schematic diagrams illustrating the prior art nickel-plating process for the aluminum alloy radiator. As shown in FIG. 1 to FIG. 3, before implementing the nickel plating process, the lower end of the aluminum alloy fin structure 1a is dipped in a xe2x80x9cZnxe2x80x9d tank 2a containing a volume of zinc solution 21a for partially zinc plating. Since the aluminum alloy fin structure 1a includes a plurality of aluminum alloy fins 11a each of which is arranged in parallel with adjacent fins with a very small interval, the dipping depth of the lower end of the aluminum alloy fin structure 1a under the liquid surface of the zinc solution 21a cannot be finely controlled; thus resulting in a zinc layer plated on the lower end of the aluminum alloy fins 11a having an elevation profile, as shown in FIG. 4. The entire aluminum alloy fin structure 1a is then dipped into a volume of nickel solution 31a in a xe2x80x9cNixe2x80x9d tank 3a for nickel plating. During the nickel plating process, only the zinc layer 12a is plated with nickel, resulting in an unpleasant black nickel layer having same elevation profile. Since the nature of inferior thermal conductivity property of nickel, the heat-dissipating performance of the aluminum alloy fin structure 1a is thus reduced. Moreover, during the nickel plating process, excess zinc residuals will remain at the intervals between the parallel aluminum alloy fins 11a, as shown in FIG. 5.
Accordingly, the primary objective of the invention is to provide an improved nickel-plating method for locally plating an aluminum alloy fins of a radiator, thereby improving thermal performance and appearance.
Another objective of the present invention is to provide a local nickel-plating method for aluminum alloy radiators. During the nickel-plating process, excess zinc residuals remained on the radiator can be recovered and reused. The consumption of nickel plated on the aluminum alloy fins may be reduced down to about one tenth of original amount.
According to the claimed invention, an improved method for locally nickel-plating an aluminum alloy fin structure is provided. The method of this invention includes: placing the aluminum alloy fin structure on a sponge that is located at the bottom of a xe2x80x9czincxe2x80x9d tank containing a volume of zinc chemical solution for zinc plating; and thereafter rotating the aluminum alloy fin structure and immersing the rotated aluminum alloy fin structure in a volume of nickel chemical solution of a xe2x80x9cnickelxe2x80x9d tank to plate nickel onto the aluminum alloy fin structure.